PureBasic

Lower-Level REST API Methods (Google Cloud Storage)

See more REST Examples

The FullRequest* methods, such as FullRequestBinary, FullRequestMultipart, FullRequestNoBody, FullRequestStream, FullRequestString, etc. are high-level REST API methods that both send the request and receive the response. It is often the case that an application needs make a REST call, but with a finer level of control. The Chilkat REST API provides this feature. An application can break a REST call into the following parts:

1. Send the HTTP request. (via the SendReq* methods)
2. Receive the HTTP response header. (ReadResponseHeader)
3. Receive the HTTP response body. (via the ReadRespBody* methods)

This example demonstrates a REST call using SendReqStringBody, ReadResonseHeader, and ReadRespBodyString.

PureBasic

IncludeFile "CkAuthGoogle.pb"
IncludeFile "CkRest.pb"
IncludeFile "CkJsonObject.pb"

Procedure ChilkatExample()

    success.i = 0

    ; This example demonstrates a REST call using SendReqStringBody, ReadResonseHeader, and ReadRespBodyString.
    ; It will create a bucket in Google Cloud Storage.

    ; It requires the Chilkat API to have been previously unlocked.
    ; See Global Unlock Sample for sample code.

    gAuth.i = CkAuthGoogle::ckCreate()
    If gAuth.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; Obtain an access token as shown in one of the following examples:
    ; See Get Access Token using a Service Account JSON Key
    ; See Get Access Token using a P12 File

    rest.i = CkRest::ckCreate()
    If rest.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; Connect using TLS.
    bAutoReconnect.i = 1
    success = CkRest::ckConnect(rest,"www.googleapis.com",443,1,bAutoReconnect)

    ; Provide the authentication credentials (i.e. the access key)
    success = CkRest::ckSetAuthGoogle(rest,gAuth)

    ; Build the JSON request body for creating a bucket.
    ; The only required property is the "name", but we'll add more
    ; to make a better example..
    jsonReqBody.i = CkJsonObject::ckCreate()
    If jsonReqBody.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkJsonObject::ckAddStringAt(jsonReqBody,-1,"name","chilkat-bucket-c")
    success = CkJsonObject::ckAddStringAt(jsonReqBody,-1,"kind","storage#bucket")
    success = CkJsonObject::ckAddStringAt(jsonReqBody,-1,"location","US")

    objVersioning.i = CkJsonObject::ckCreate()
    If objVersioning.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkJsonObject::ckAppendObject2(jsonReqBody,"versioning",objVersioning)
    success = CkJsonObject::ckAddBoolAt(objVersioning,-1,"enabled",1)

    ; Show the HTTP request body we'll be sending.
    Debug CkJsonObject::ckEmit(jsonReqBody)

    ; Add the required query parameter.
    ; See https://cloud.google.com/storage/docs/json_api/v1/buckets/insert
    success = CkRest::ckAddQueryParam(rest,"project","chilkattest-1050")

    ; Add the Content-Type HTTP request header.
    success = CkRest::ckAddHeader(rest,"Content-Type","application/json; charset=UTF-8")

    ; Send the REST HTTP request.
    success = CkRest::ckSendReqStringBody(rest,"POST","/storage/v1/b",CkJsonObject::ckEmit(jsonReqBody))
    If success = 0
        Debug CkRest::ckLastErrorText(rest)
        CkAuthGoogle::ckDispose(gAuth)
        CkRest::ckDispose(rest)
        CkJsonObject::ckDispose(jsonReqBody)
        CkJsonObject::ckDispose(objVersioning)
        ProcedureReturn
    EndIf

    ; Read the response header.
    responseStatusCode.i = CkRest::ckReadResponseHeader(rest)
    If responseStatusCode < 0
        ; We were unable to receive the response header.
        Debug CkRest::ckLastErrorText(rest)
        CkAuthGoogle::ckDispose(gAuth)
        CkRest::ckDispose(rest)
        CkJsonObject::ckDispose(jsonReqBody)
        CkJsonObject::ckDispose(objVersioning)
        ProcedureReturn
    EndIf

    If responseStatusCode <> 200
        ; The response was not successful.  We'll still need to receive 
        ; the response body, which may contain an error message from the server.
        ; If the response has no body, then the method for reading the
        ; response body can still be called.  It will simply return with an empty
        ; response body.

        ; We can examine the response header and status text:
        Debug "Response status text: " + CkRest::ckResponseStatusText(rest)
        Debug "Response header: " + CkRest::ckResponseHeader(rest)
    EndIf

    ; Read the response body.  In this case we're expecting it to be JSON..
    responseBodyStr.s = CkRest::ckReadRespBodyString(rest)
    If CkRest::ckLastMethodSuccess(rest) <> 1
        ; We were unable to receive the response body.
        ; Note: If the response did not include a body (such as for cases where
        ; the Content-Length header is 0, or if the response status code implicitly
        ; indicates no body, then ReadRespBodyString returns cktrue, and the
        ; responseBodyString will be an empty string.
        Debug CkRest::ckLastErrorText(rest)
        CkAuthGoogle::ckDispose(gAuth)
        CkRest::ckDispose(rest)
        CkJsonObject::ckDispose(jsonReqBody)
        CkJsonObject::ckDispose(objVersioning)
        ProcedureReturn
    EndIf

    ; Show the JSON response.
    Debug "Json Response: " + responseBodyStr


    CkAuthGoogle::ckDispose(gAuth)
    CkRest::ckDispose(rest)
    CkJsonObject::ckDispose(jsonReqBody)
    CkJsonObject::ckDispose(objVersioning)


    ProcedureReturn
EndProcedure